How to use SQL Server Transaction inside T-SQL TRY...CATCH block

Question

I have sample T-SQL code below, BEGIN TRY

BEGIN TRY    
BEGIN TRANSACTION 

    RESTORE FILELISTONLY
    FROM DISK = 'D:\Backup\MyDatabase.bak'
    GO

    ALTER DATABASE MyDatabase
    SET SINGLE_USER WITH
    ROLLBACK IMMEDIATE

    ALTER DATABASE MyDatabase 
    SET RECOVERY Simple

    ----Restore Database
    RESTORE DATABASE MyDatabase
    FROM DISK = 'D:\Backup\MyDatabase.bak'
    WITH MOVE 'MyDatabase' TO 'C:\DataFolder\MyDatabase.mdf',
    MOVE 'MyDatabase_log' TO 'C:\DataFolder\MyDatabase_log.ldf'

    ALTER DATABASE MyDatabase SET MULTI_USER

    GO

    USE [MyDatabase]
    IF NOT  EXISTS (SELECT * FROM sys.database_principals WHERE name = N'user1')
    CREATE USER [user1] FOR LOGIN [user1] WITH DEFAULT_SCHEMA=[user1]
    GO

    EXEC sp_addrolemember 'db_owner',N'user1'
    GO
    COMMIT
    --Send email on successfull execution of script
    USE  [msdb];
    EXEC sp_send_dbmail @profile_name='My Mail Profile',
    @recipients='myemail@mydomain.org',
    @subject='Test subject',
    @query = '',
    @body='Tested successfully.'
    END TRY
    BEGIN CATCH
    --If there is any error in the script, roll back the transaction and also send an error report email notification
    ROLLBACK
    USE  [msdb];
    EXEC sp_send_dbmail @profile_name='My Mail Profile',
    @recipients='myemail@mydomain.org',
    @subject='Test error',
    @body= ERROR_MESSAGE()
    END CATCH

That code throws the following errors,

1. Msg 102, Level 15, State 1, Line 4 Incorrect syntax near 'D:\Backup\MyDatabase.bak'.

2. Msg 102, Level 15, State 1, Line 10 Incorrect syntax near 'BEGIN'.

3. Msg 102, Level 15, State 1, Line 17 Incorrect syntax near ')'.

But if i move the code out of the BEGIN TRY and BEGIN TRANSACTION blocks, it executes successfully with out any errors.

All i want to achieve is to execute that T-SQL script and if it fails i notify i send a notification to some email account with the error message that made the code fail in the email body.

Any suggestions on how i can better achieve this are very welcome.

Answer 1

TRY/CATCH blocks can only be used inside the scope a single request (batch). You are trying to span a TRY block over several batches. GO is the default batch delimiter, fyi.

You also expect to support transactions and rollback for some operations that do not support transactions, like RESTORE:

RESTORE is not allowed in an explicit or implicit transaction.

You would have a much better chance at handling this kind of problems at a higher level, in an app or even is a script. Note that sqlcmd supports the -b option to break on first error, and you can use the exit code (%ERRORLEVEL%).

Answer 2

the first problem is the "go" statement in line 5 ... sql server tries to execute the lines up to this point and that doesn't work because you have a begin try without corresponding end try ...